This invention relates to a trolley transfer unit for a tunnel furnace, and more particularly to a transfer unit to be used between trolleys when ceramic sintered products are loaded onto or unloaded from trolleys.
As shown by way of example in FIG. 1, with a trolley transfer system for a tunnel furnace hitherto used, there is provided a tunnel furnace 1 for sintering products, a return track 2 in parallel with the tunnel furnace 1 and connecting passages 3a and 3b. After removal of sintered products from trolleys 4 used for sintering the products in the tunnel furnace 1 according to a predetermined schedule, the trolleys are transferred to the return track 2 by means a transfer car 5a in the connecting passage 3a. The transferred trolleys 4 are progressively forced into the entrance of the return track 2 by means of trolley feeding means 6 so that a predetermined number of the trolleys 4 are gathered together in the return track 2. On the other hand, on an exit side of the return track 2 the trolleys are forced out of the return track 2 into the connecting passage 3b one by one every time when one trolley 4 is forced into the return track 2. The trolley 4 forced into the connecting passage 3b is transferred toward the tunnel furnace 1 by means of a transfer car 5b. The transferred trolleys 4 are progressively forced into an entrance of the tunnel furnace 1 by means of trolley feeding means (not shown). The trolleys in the tunnel furnace 1 and the return track 2 are closely gathered in an end-to-end relation always to keep constant numbers of the trolleys 4 in the furnace and return track, respectively.
In the trolley transfer system described above, since the trolleys 4 are gathered and connected from the entrance to the exit of the return track 2, the system encounters the following disadvantages.
1. There is no clearance between the trolleys. Therefore, it is difficult if not impossible for operators to move through clearances between the trolleys.
2. It is required to provide the trolleys 4 in the return track 2 in the same number as that of the trolleys 4 in the tunnel furnace 1.
3. In case a problem occurs in the lower portion of the trolley 4 in the return track 2, it is impossible to repair the troubled portion of the trolley at the location.
4. In the event that refractory bricks constituting the trolley are damaged, the damaged trolley, often improperly urges the preceding trolley so that refractory bricks of the preceding trolley are damaged and positions of the shelf assembly are shifted.